Conventional structural paradigms consist of a heavy and rigid primary structure coupled with a secondary morphing system to achieve the displacement control required for high precision applications. These rigid primary structures are required to be very heavy. Terrestrially, sparse apertures, such as the Navy Precision Optical Interferometer (NPOI), exist. The NPOI uses six telescopes, mounted to bedrock, placed along three 250 meter arms joining the light to create a single image with much higher resolution than is capable to achieve using any of the six individual telescopes. A key problem is phasing the photons from each individual telescope back together to create an effective single optical surface. This is done using fine and course actuators to ensure that the distance the light travels from each individual optical mirror assembly to the optical sensor is the same. The sparsity of this system is less than 1% but it has produced the highest resolution optical images of any astronomical instrument to date. Replicating this system in orbit to create a large coherent mirror is difficult. The methodology used to date with James Web Telescope and others consists of a heavy structure used as the rigid and invariant foundation for the coarse and fine actuation control to deliver the displacement accuracy required. The development of this thermally stable extremely stiff primary structure introduces significant mass requirements that increase the cost of the system.
Lower accuracy smart morphing systems such as hexapod morphing systems (Stewart platforms) have been implemented with success. The hexapod has been shown to be a versatile simple morphing system able to provide low accuracy morphing systems. The conventional hexapod is reliant on classical actuators to act as both the structural connection and the actuation method. The conventional actuators used in hexapods are not able to provide sufficient control capability to achieve the high precision morphing capability. Furthermore having the actuator as the primary load path reduces the stiffness of the system relative to the invention reducing structural performance. The hexapod is also not structurally efficient and has some dynamic complexities due to the kinematic nature of the design.
As the quest for higher resolution telescopes drive the size of optical apertures larger and larger the structural methodology needs to adapt to meet these challenges. Conventional systems, with a single solid primary (monolithic) mirror, are limited by spacecraft volume and mass as well as the exponential scaling of mirror manufacturing costs. Monolithic mirror technology, like the Hubble Telescope, is already at the limit of financial feasibility and to achieve more operational capability new geometries and technologies must be investigated. Sparse aperture optical systems can be made cost effective by using several smaller and therefore much lower cost mirrors that are phased together creating an effectively much larger mirror using a complex structural and secondary optical system. Segmented mirror telescopes like JWST have achieved phasing on the scales of IR but the ability to achieve phasing for sparse apertures in the optical range, at low cost, would enable missions that are impossible today.